<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script>
			
			let age = +prompt('请输入您的年龄',0);
			
			let result = age >= 18 ? '成年' : '未成年';
			console.log(result);
		</script>
	</body>
</html>